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840mg Biplane

I built this back in May of '07. With this plane I wanted to focus primarily on small size. I was still going for something lighter than my previous plane but I wanted to make an airplane that even I thought was small - a tall order considering I had been building micro r/c planes for year or two at this point.

I chose a biplane design for this plane because it would allow me to keep a high wing area but keep the wing span small. The wing span on this plane is 2.75", the chord is 7/8", and the length is 3.75". The frame is all made of balsa wood and covered with OS film. Flight times were in the 4-5 minute range per charge.

It is powered by a 3.2mm diameter brushed motor and a 1" propeller. The infrared receiver is capable of controlling the throttle and the rudder with a 7 step proportional control. The rudder is driven with a small electromagnetic actuator. The power source was a single cell 10mAh lithium polymer battery which can be recharged.

About a year or so after I built this I replaced the balsa paddle prop with a slick carbon fiber one that one of my friends designed. Not only did that prop increase the flight time but it made the plane basically silent. When it got within 5-10 feet of you it sounded like a mosquito about 1ft from your ear.

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